✍ Scribed by C. Goze Bac; P. Bernier; S. Latil; V. Jourdain; A. Rubio; S.H. Jhang; S.W. Lee; Y.W. Park; M. Holzinger; A. Hirsch
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We report on nuclear magnetic resonance on single wall carbon nanotubes. Depending on the chemical preparation the electronic and dynamical properties of carbon nanotubes are presented and discussed. From a room temperature study of the spin lattice relaxation of carbon nanotubes prepared with various catalysts we clearly identi®ed two components. In agreement with previous NMR studies and theoretical predictions, one-third of the intensity of the signal is found with a short relaxation time (about 5 s) attributed to metallic nanobutes while the rest of the signal presents a relaxation time of about 90 s corresponding to semiconducting nanotubes. In the case of oxidized or cut nanotubes only one relaxation time is observed with characteristics similar to the slow component. The disappearance of the fast relaxing component is associated with the absence of metallic nanotubes damaged by the chemical or mechanical treatments. In this case, the T dependence of the spin lattice relaxation reveals the eect of thermally activated small amplitude motions (twistons) of the nanotube in ropes. If diusion of twistons might induce movement of 13 C sites and local magnetic ®eld ¯uctuations, orientational order could appear below the transition temperature of 170 K. In the last part, we present the theoretical predictions of chemical shift tensor in carbon nanotubes.
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We have performed 13 C nuclear magnetic resonance (NMR) measurements on single-walled carbon nanotubes. Spectrum, shift, linewidth, and T 1 have been measured as a function of temperature from 4.6 K to 200 K under the magnetic field of 4.7 T. Spectrum shows a narrow lineshape for the 13 C nucleus. S
## 13 C NMR spectra and spin-lattice relaxation times were measured for single-wall carbon nanotubes with 99.9 and 50.0% 13 13 13 C enrichments and natural abundance (1.1% C) prepared by catalytic decomposition of CH . The C isotropic shift is 4 about 116 ppm from tetramethylsilane, being estimate
13CNMR chemical shifts of 23 aniline and 1.8diaminonaphthalene derivatives are reported; the parent compounds are also included for purposes of comparison.
## Abstract The tetraphenyl–metal, hexaphenyl–dimetal, and triphenylchloro–metal derivatives of the Group IV elements were examined using ^13^C NMR methods. Chemical shifts and metal–carbon coupling constants were obtained for all compounds studied.